Motor fuel containing octane appreciator



United States Patent 6 3,181,938 MGTOR FUEL CONTABNING OCTANE APPRECIATOR George W. Eekert, Wappingers Falls, and Harry Chafetz, Poughkeepsie, N.Y., assignors to Texaco Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed July 13, 1959, Ser. No. 826,474 9 Claims. (Cl. 44-69) This invention relates to a hydrocarbon fuel of high octane rating. More specifically, it involves the discovery that the octane rating of leaded gasoline fuels of prescribed composition is substantially improved by the addi tion thereto of an ester of a keto alcohol and a monocarboxylic acid wherein the acyloxy radical is attached to a tertiary carbon atom.

The recent increases in compression ratios of automobile engines have placed a severe strain on petroleum refiners to produce fuels having the octane rating demanded by these engines. Premium fuels at the present time have research octane ratings between 97 and 100 and it has been predicted that premium fuels will have to have octane ratings between 105 and 110 five years from now in order to satisfy the octane requirements of the high compression automotive engines predicted for that date. In order to produce premium fuels of octane ratings of 95 and above, it has been necessary for refiners to rely heavily on catalytic refining operations such as fluid catalytic cracking, catalytic reforming, alkylation and catalytic isomerization.

Catalytic cracking and catalytic reforming, which are the most Widely used refining operations in the production of high octane fuels, produce substantial quantities of aromatics; catalytic cracking also produces a substantial amount of olefins. It is well known that olefins and aromatics, although possessing high octane ratings, have a poorer response to organo-lead compounds such as tetraethyl lead than saturated aliphatic gasoline components. Accordingly, as the aromatic and olefinic content of the gasolines have increased to meet the octane levels required by modern automotive high compression engines, the lead response of the resulting fuels has diminished. Stated another way, the octane increment obtainable by the addition of an organo-lead compound decreases as the aromatic and olefin contents of the base fuel increase. The subject invention involves the discovery that the octane rating of leaded motor fuels containing a substantial concentration of high octane components, that is, aromatic, olefins and mixtures thereof, is markedly improved by the addition of a small amount of keto esters of prescribed composition.

In commonly-assigned copending application Serial No. 89,466, filed October 11, 1957, it is disclosed that hydrocarbyl monocarboxylic acids substantially raise the octane rating of a motor fuel containing an organo-lead antiknock agent and a substantial concentration of high octane components which may be aromatic hydrocarbons, olefinic hydrocarbons or mixtures thereof. In another commonly-assigned copending application Serial No. 699,- 944, filed December 2, 1957, now abandoned, it is disclosed that t-alkyl esters of hydrocarbyl monocarboxylic acids have a similar octane appreciating action in leaded motor fuels of the same composition. The subject invention involves the discovery that esters of monocarboxylic acids and keto alcohols wherein the acyloxy radical is attached to a tertiary carbon atom also have an octane appreciating action in leaded motor fuels of the prescribed type.

The high octane hydrocarbon motor fuel of this invention comprises high octaife components including a sub stantial concentration of aromatic hydrocarbons, olefinic hydrocarbons or mixtures thereof, an organo-lead antiknock agent and an ester of a monocarboxylic acid and a keto alcohol wherein the acyloxy radical is attached to a tertiary carbon atom in a minimum concentration of 0.1 volume percent of the motor fuel.

The action of keto esters having the acyloxy radical attached to a tertiary carbon atom in appreciating the octane rating of gasoline is characterized by several unusual features. In the first instance, the keto esters of prescribed composition appear to be ineffective in raising the octane rating of gasoline unless an organo-lead antiknock agent, normally tetraethyl lead, TEL, is a component of the gasoline mixture. The second unusual characteristic of the action of keto esters in appreciating the octane rating of gasolines is the fact that an equivalent concentration of keto ester appears to cause a greater octane improvement above the 100 octane level than below the 100 octane level. The third unusual feature of the action of keto esters of prescribed composition is that they appear to have substantially little effect on the octane rating of a gasoline consisting essentially of saturated aliphatic hydrocarbons even though an organo-lead antiknock agent is present.

Since organo-lead anti-knock agents exert their greatest octane appreciation in predominantly saturated paraffinic base hydrocarbon gasolines and have the least effect on the octane rating of aromatic and olefin-rich gasolines, the present invention neatly complements tetraethyl lead as an octane improver. Keto esters having the acyloxy radical attached to a tertiary carbon atom have their minimum effect where tetraethyl lead has its maximum effect and exert their maximum effect on octane values where tetraethyl lead has its minimum effect.

The novel fuel compositions of this invention have a minimum concentration of aromatic and/ or olefin components of at least 10 volume percent. The aromatic and/ or olefin components of the motor fuel of the invention can constitute as high as 100 volume percent thereof but usually comprise between 20 and volume percent. A 10 percent concentration of aromatics and/or olefins appears to be necessary for keto esters to exert a significant octane improvement.

The aromatic components of the motor fuel of the invention are generally supplied by catalytic reforming or catalytic cracking operations. Catalytic reformate is particularly high in aromatics. The olefin components of the motor fuel of the invention are derived either from thermal cracking, catalytic cracking or polymerization.

The organo-lead reagent necessary for the action of keto esters as octane improvers is usually a tetraalkyl lead compound. Tetraethyl lead is universally used as an antiknock agent but other tetraalkyl lead compounds such as tetramethyl lead, tetrabutyl lead, tetraamyl lead, tetrapropyl lead, etc., possess anti-knock properties and may be used in the fuel compositions of the inevntion in conjunction with keto esters of prescribed composition.

The tetraethyl lead mixtures commercially available for automotive use contain an ethylene chloride-ethylene bromide mixture as a scavenger for removing lead from the combustion chamber in the form of volatile lead halides. Tetraethyl lead fluid, the commercial product, comprises tetraethyl lead, ethylene chloride and ethylene bromide, the latter two reagents being present in 1.0 thecry and 0.5 theory, respectively, theory denoting the stoichiornetric amount required for reaction with the lead content of the tetraethyl lead.

The organ c-lead reagent is present in the fuel compositions of the invention in concentrations between 0.5 ml. per gallon up to the statutory limit of organo-lead reagent concetration which, at the present time, is 3 ml. per gallon in the case of automotive fuel and 4.6 ml. per gallon in the case of aviation fuel. The usual concentration of tetraethyl lead is between 1 and 3 ml. per gallon in (Q a automotive gasoline and 2 to 4.6 ml. per gallon in aviation gasoline.

Keto esters which are effective in increasing the octane rating of aromatic and/ or olefin-containing gasoline have the general formula:

ll (mic (R )uC R3 o o o 11' wherein R is an aliphatic hydrocarbyl radical containing l-8 and prefer-ably 1-4 carbon atoms, R is a hydrocarbyl radical containing l-l2 and preferably 1-8 carbon atoms, R is a divalent aliphatic hydrocarbyl radical containing l-6 carbon atoms, R is an aliphatic hydrocarbyl radical containing 1-8 and preferably 1-4 carbon atoms and n is or 1.

Examples of effective keto esters having the acyloxy radical attached to a tertiary carbon atom are the following: 4-methyl-4-acetoxy-2-pentanone (the acetate of diacetone alcohol), 4-methyl-4-propionoxy-2-pentanone (the propionate of diacetone alcohol), 4-methyl-4-capryloxy-2-pentanone (the caprylate of diacetone alcohol), 4 methyl 4 acetoxy 2 hexanone, 4 ethyl 4 propionoxy 3 hexanone, 5 methyl 5 acetoxy 3 octanone, 4 methyl 4 benzoxy 2 pentanone, 6 methyl- 6-butyroxy-2-octanone, 4-ethyl-4-propionoxy-2-hexanone, and S-methyl-S-(Z-ethylhexanoxy)-3-nonanone.

The keto ester of prescribed composition must be present in a minimum concentration of 0.1 volume percent before a significant octane appreciation is realized. Below the minimum prescribed concentration of 0.1 volume percent no measurable octane appreciation is obtained in a leaded gasoline containing the prescribed aromatic and/or olefin content. The preferred concentration of keto ester falls between about 0.3 and 2.0 volume percent with maximum octane appreciation usually being obtained at a concentration level between 0.5 and 1.5 volume percent. Octane appreciation is obtained with keto ester concentrations as high as about 5.0 volume percent but economic considerations preclude the use of such concentrations in commercial fuel compositions. Moreover, there appears to be a significant decrease in octane appreciation as the keto ester concentration exceeds about 1.5 volume percent of the gasoline composition.

In Table I there is shown the effectiveness of keto estcrs having the acyloxy radical attached to a tertiary carbon atom in raising the octane rating of a leaded fuel composition containing the prescribed aromatic and/or olefin content. The base fuel employed in Table I had a Research Octane Number (RON) of 105, a Motor Octane Number (MON) of 98.5 and comprised approximately 10 volume percent n-butane, 40% isobutyleneisobutane alkylate, 10% pentenes from fluid catalytically cracked naphtha and 40% heavy platformate; the base fuel contained 3 cc. of tetraethyl lead (TEL) per gallon. Fluorescent Indicator Analysis (FIA) of this base fuel indicated an aromatic content of approximately 35% and an olefin content of approximately 6%; its initial boiling point was 90 F. and its end point was 367 F.

TABLE I Increase in RON Base fuel +0.5 v. percent diacetone alcohol acetate 1.3 Base fuel +0.75 v. percent diacetone alcohol acetate- 1.8 Base fuel +1.0 v. percent diacetone alcohol acetate 2.2

The data in the foregoing table demonstrate the effectiveness of esters of keto alcohols wherein the acyloxy radical is attached to a tertiary carbon atom in raising the octane rating of leaded gasoline containing the prescribed aromatic and/or olefin content.

In Table II there is shown the action of keto esters of prescribed compositions in a commercial premium motor fuel having an RON of 100.4. The premium motor fuel employed in Table II contained 3 cc. of TEL per gallon and had an IBP' of 89 F. and an end point of 372 R;

L1 FIA indicated that it comprised approximately 50% saturated hydrocarbons, 30% aromatics and 20% olefinic hydrocarbons.

TABLE II Units improvement in octane rating by keto esters in premium fuel Increase in RON Base fuel +0.75 v. percent diacetone alcohol acetate- 1.5

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A hydrocarbon fuel in the gasoline boiling range containing an organo-lead anti-knock agent, at least 10 volume percent high octane components selected from the group consisting of olefinic hydrocarbons, aromatic hydrocarbons and mixtures thereof, and an ester of a keto alcohol and a hydrocarbyl monocarboxylic acid, said ester having the general formula:

l1 N U M R O 0 CR wherein R is an aliphatic hydrocarbyl radical containing 18 carbon atoms, R is a hydrocarbyl radical containing 1-12 carbon atoms, R is a divalent aliphatic hydrocarbyl radical containing 16 carbon atoms, R is an aliphatic hydrocarbyl radical containing l-8 carbon atoms and n is an integer selected from the group consisting of 0 and 1 and being present in a concentration between 0.1 and 5.0 volume percent.

2. A hydrocarbon fuel according to claim 1 in which said organo-lead anti-knock agent is present in a concentration between 0.5 and 4.6 cc. per gallon.

3. A hydrocarbon fuel in the gasoline boiling range containing a tetraalkyl lead anti-knock agent in a concentration of at least 0.5 cc. per gallon, high octane components selected from the group consisting of olefinic hydrocarbons, aromatic hydrocarbons and mixtures thereof in a concentration of at least 10 volume percent of said fuel and an ester of a keto alcohol and a hydrocarbyl monocarboxylic acid having the general formula:

II (Hammers O O C R wherein R is an aliphatic hydrocarbyl radical containing 1-8, R is a hydrocarbyl radical containing 1-12, R is a divalent aliphatic hydrocarbyl radical containing 1-6 carbon atoms, R is an aliphatic hydrocarbyl radical containing 1-8 and n is an integer selected from the group consisting of 0 and 1, said ester beinig present in a concentration between 0.1 and 5.0 volume percent whereby a substantial improvement of the octane rating of said tetraalkyl lead-containing fuel is effected.

4. A hydrocarbon fuel according to claim 3 in which the concentration of said ester is between 0.3 and 2.0 volume percent.

5. A hydrocarbon fuel according to claim 3 containing 1.0-4.6 cc. per gallon of tetraethyl lead.

6. A hydrocarbon fuel according to claim 3 in which said high octane components constitute 20-80 volume percent of said fuel.

7. A hydrocarbon fuel according to claim 3 in which said ester is diacetone alcohol acetate.

8. A hydrocarbon fuel in the gasoline boiling range containing a tetraalkyl lead antiknock agent, at least about 10 volume percent high octane components selected from the group consisting of olefinic hydrocarbons, aromatic hydrocarbons and mixtures thereof and a compound having the formula wherein R is a monovalent aliphatic hydrocarbon radical of 1-8 carbon atoms and R is selected from the group consisting of hydrogen and R in an amount sui'ficient to improve the octane rating of said hydrocarbon fuel.

9. A hydrocarbon fuel in the gasoline boiling range containing a tetraalkyl lead antiknock agent, at least about 10 volume percent high octane components selected from the group consisting of olefinic hydrocarbons, aromatic hydrocarbons and mixtures thereof and a compound having the formula wherein R is an alkyl radical having from 1 to 8 carbon atoms in an amount suflicient to improve the octane rating of said hydrocarbon fuel.

References Cited by the Examiner UNITED STATES PATENTS 2,150,349 3/38 Van Peski et al. 252-386 2,210,942 8/40 Lipkin 44--77 2,228,662 1/41 Holm 44-70 2,280,474 4/42 Byrkit et al. 4469 2,314,575 3/43 Doran 44-68 2,360,585 10/44 Ross et a1 44-80 FOREIGN PATENTS 517,212 10/55 Canada.

837,965 11/38 France.

277,326 1/29 Great Britain.

OTHER REFERENCES Improved Motor Fuels Through Selective Blending, by Wagner et al., paper presented before the 22nd Annual Meeting of the American Petroleum Institute, Nov. 7, 1941, pages 8-13.

20 DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, ALPHONSO D. SULLIVAN,

Examiners. 

1. A HYDROCARBON FUEL IN THE GASOLINE BOILING RANGE CONTAINING AN ORGANO-LEAD ANTI-KNOCK AGENT, AT LEAST 10 VOLUME PERCENT HIGH OCTANE COMPONENTS SELECTED FROM THE GROUP CONSISTING OF OELFINIC HYDROCARBONS, AROMATIC HYDROCARBONS AND MIXTURES THEREOF, AND AN ESTER OF A KETO ALCOHOL AND A HYDROCARBYL MONOCARBOXYLIC ACID, SAID ESTER HAVING THE GENERAL FORMULA: 